In the dental enamel art, translucency (the inverse of opacity) is a characteristic which is essential and improvements of 5 percent or more are widely recognized as being significant improvements in the art particularly when accompanied by acceptable wear resistance.
It is greatly preferred that dental enamel material be effectively homogeneous such that air bubbles or structural discontinuities are substantially avoided from introduction into the tooth structure. Additionally, it is preferred that such materials be capable of deforming a matrix band during the course of tooth filling. Such materials should also be capable of withstanding the physical stresses extant in the posterior region of the mouth and not crumble, fracture or erode under such conditions.
Opacity as used herein refers to the percentage of impinging white light transmitted from a spectrophotometer through a 1 mm thick sample of material being tested. More specifically, as used herein opacity of the sample of material, which is not pigmented, is measured using a Macbeth Color Eye Spectrophotometer calibrated according to the manufacturer's calibration method CAL-030-95, with the spectrophotometer connected to a CompuAid 286 microcomputer.
Localized wear volume loss (also known as volume loss of localized wear) as used herein refers to the volume loss in mm from a sample of material being tested after 250,000 cycles in a Leinfelder in vitro wear testing device as described in Leinfelder et al in An In Vitro Device for Predicting Clinical Wear, Quintessence International, Volume 20, Number 10/1989, pages 755-761. Measurements may be made for example using a VCA 2500 Video Contact Angle System, sold by AST Products, Inc., Billerica, Mass., and a microcomputer with MicroSoft Windows software, in accordance with the AST products User's Manual. The wear pistons are calibrated with the return limit set to 8.3 mm, load set to 10Kg Maximum, (the load applied to the piston being from 7.6 to 8.0 Kg), Crosshead speed set to 200 mm/min. Such device is in use at University of Alabama, University of North Carolina, Creighton University and at DENTSPLY International Inc.
Localized extended wear volume loss as used herein refers to the volume loss in mm.sup.3 from a sample of material being tested after 400,000 cycles in a Leinfelder in vitro wear testing device as described in Leinfelder et al in An In Vitro Device for Predicting Clinical Wear, Quintessence International, Volume 20, Number 10/1989, pages 755-761. Measurements may be made for example using a VCA 2500 Video Contact Angle System, sold by AST Products, Inc., Billerica, Mass., and a microcomputer with MicroSoft Windows software, in accordance with the AST products User's Manual. The wear pistons are calibrated with the return limit set to 8.3 mm, load set to 10 Kg Maximum, (the load applied to the piston being from 7.6 to 8.0 Kg), Crosshead speed set to 200 mm/min. Such device is in use at University of Alabama, University of North Carolina, Creighton University and at DENTSPLY International Inc.
In measuring material volume loss the sample from the Leinfelder University of Alabama wear machine is measured for wear in the Form Taysurf profilometer which employs a transversing stylus to construct a 3D topographic map of the worn area by means of an electronic interface unit linked to a host computer. A surface analyzer program installed in the host computer graphically depicts the worn area and calculates its volume. This volume, expressed in cubic millimeters, is regarded as the "wear volume loss" of the material tested. The higher the volume loss, the greater the material wears.
The index of refraction (or refractive index) for any substance is the ratio of the velocity of light in a vacuum (Air at one atmospheric pressure is commonly used in place of a vacuum) to its velocity in the material being tested.
Liquid refractive index as used herein refers to the refractive index of a liquid. Preferably liquid refractive index as used herein is measured by a refractometer-Abbe Model (manufactured by BAUSH & LOMB).
Filler refractive index as used herein refers to the refractive index of inorganic filler particles. Preferably filler refractive index as used herein is that provided by the manufacturer, and may be measured, for example using a microscope.
Contrast ratio of dental composite is the ratio between the daylight apparent reflectance of the specimen when backed by a black standard and the reflectance of the specimen when backed by a white standard. The translucency of composite material is dependent on the particle size, shape and the difference in refractive indices between the glass filler and resin matrix in which the glass powders are located. The substantially perfect match (effective equality) in the refractive indices between inorganic glass filler and organic resin matrix used in the material of the invention results in the improved translucency of the dental enamel material of the invention.
Ethoxylated Bisphenol A Dimethacrylate (EBPADMA) also known as 2,2-Bis[4-(2-methacryloxyethoxy)phenyl]propane has the structural formula: ##STR1##
and is used as a resin matrix.
Triethylene glycol dimethacrylate also known as 2,2'[Ethanediylbis(oxy)bisethyl-di-2-methyl-propenate has the structural formula: ##STR2##
and is used as resin matrix.
Cyclodi-2,2'-bis{4-[3-methacryloxy-2-(1,12-dioxa-2,11-dioxo-3,10-diazadodec ane)propoxy]phenyl} Propane (NCO Monomer) has the structural formula: ##STR3##
and is used as a resin matrix.
1,7,7,Trimethylbicyclo[2.2.1]heptane-2,3 dione (camphorquinone or CQ).
Ethyl-(4-N,N-dimethylamino)benzoate (EDAB) is a VLC initiating system and has a structural formula: ##STR4##
Butylated Hydroxy Toluene (BHT) also known as 2,6-bis(1,1-dimethylethyl)-4-methylphenol is a stabilizer having the structural formula: ##STR5##
(2-Hydroxy-methoxyphenyl)phenyl Methanone is a UV stabilizer having the structural formula: ##STR6##
and sold by BASF Corporation as Uvinul M40.
Diethyl 2,5-dihydroxyterephthalate is a fluorescing agent having the structural formula: ##STR7##
and is sold by Riedel-de Haen AG as Lumilux.RTM. Blau LZ.
2,7,7,9,15-Pentamethyl-4,13-dioxo-3,14-dioxa-5,12-diaza-hexadecane-1,16-diy ldimethacrylate (UDMA) has a structural formula: ##STR8##